The work proposed deals with embryonic development and differentiation in the common snapping turtle, Chelydra serpentina. The current objectives are as follows: 1) A further analysis of the temperature-sensitive periods during incubation which are determinants of either male or female differentiation. 2) Histological study of pre-and post-hatching differentiation of the male and female which are produced by appropriate incubation temperatures. 3) Production of intersexes by proper balancing of incubation temperatures and their post-hatching differentiation. 4) Facilitation of work by other investigators on problems involving development in the turtle. BIBLIOGRAPHIC REFERENCES: C.L. Yntema 1976 Effects of incubation temperatures on sexual differentiation in the turtle, Chelydra serpentina. J. Morph., 150: 453-462. M.T. Tseng and C.L. Yntema 1976 Fine structure of the chromophobe in the pars distalis of the common snapping turtle, Chelydra serpentina. Cell. Tiss. Res., 166: 235-240.